After two years of work, since the 3.50 release, Fyodor announced the Nmap Security Scanner version 4.00. Changes since version 3.50 include a rewritten (for speed and memory efficiency) port scanning engine, ARP scanning, a brand new man page and install guide, runtime interaction, massive version detection improvements, MAC address spoofing, increased Windows performance, 500 new OS detection fingerprints, and completion time estimates. Dozens of other important changes - and future plans for Nmap - are listed in the release announcement. Fyodor also gave an interview on 4.00.